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OPA659: Adder for 10MHz signals

li cunxu
Prodigy 120 points
Part Number: OPA659

Tool/software:

Hi TI expert

    There is a 10MHz triangle wave and a fixed voltage to make an adder output, the triangle wave amplitude is ±0.2V, I use opa659, GBP is 350MHz, the following figure is the simulation file, from the simulation results, the output waveform is distorted?

OPA659 summing amplifier 250613.TSC

  • +1
    TI__Genius 16505 points

    Hi,

    For most of our high-speed devices, we tune our amplifiers for certain feedback resistances, as higher Rf values can sometimes alter the behavior of the circuit and can also result in stability issues. For this device, we suggest around 250ohm feedback resistance for a gain of 2V/V. I was able to try this with the TINA simulation, and it did improve the output signal. The table showing the recommended feedback resistors for different gains can be found in page 15 of the datasheet.

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    Prodigy 120 points

    Hi

    Thank you for your reply. I change resistor from 5kohm to 250ohm, and it improve the output signal.